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(2007/10/02)1,3,8-trimethyl-7-phenyl-1H,8H-imidazo[2,1-f]purine-2,4-dione
8-benzyl-1,3-dimethyl-7-phenyl-1H,8H-imidazo[2,1-f]purine-2,4-dione
1,3-dimethyl-7,8-diphenyl-1H,8H-imidazo[2,1-f]purine-2,4-dione
6,8-dimethyl-2-phenyloxazolo<3,2-f>xanthine
3-bromo-2-phenyl-8-methyloxazolo<3,2-f>xanthine